1. Field of the Invention
The present invention relates generally to a beverage brewing apparatus, and more particularly to a programmable brewing apparatus with “pulse” brewing and pre-infusion brewing capabilities.
2. Description of Related Art
The art of coffee brewing has advanced significantly over the last few decades from the old fashioned percolators to today's state of the art automatic brewing machines. But the goal of coffee machines has remained the same—draw the appropriate amount of flavored solutes and oils from the ground coffee beans without extracting the bitter residues and complex compounds that are released when the coffee is overbrewed. Releasing the appropriate flavor from coffee is a process that optimally considers the type of coffee, the temperature of the infusing water, the exposure time of the grounds to the infusing liquid, the level of wetting achieved by the infusing water, and so forth. A brewing apparatus that accounts for the variations and factors that affect the brewing of an optimal cup of coffee has a higher probability of success than those machines that do not account for such factors.
One factor that is critical to successful extraction of the coffee solutes is the level of wetting that the coffee brewing apparatus achieves in connection with the infusion of hot water through and about the coffee grounds. Coffee grounds are naturally coated with a fine layer of oil that is hydrophobic, that is, the coating insulates the grounds against wetting by repelling or resisting the infusing water. When water is delivered to a batch of coffee grounds, the water will create paths through the grounds that resists wetting of all grounds at the expense of overexposure of some grounds to the infusion liquid. This phenomenon results in inconsistent brewing batches because even if the grounds for each batch is measured accurately, the lack of consistent wetting results in some batches being over wetted while other batches are under wetted. This is an unsatisfactory condition that requires addressing. This layer also causes the individual grounds to float on pools of collecting water, which inhibits the full extraction of the grounds' flavor. It is important to prevent or limit the degree of floatation that the grounds experience during the brewing operation.
It has been discovered that infusing water intermittently into the brewing chamber (“pulse brewing”) increases the wetting of the grounds and promotes more uniform brewing. By introducing pulses of water into the grounds, turbulence is created that jostles and moves the coffee grounds within the brewing chamber. As the grounds move and the water mixes with the grounds, the thin oily coating on the grounds dissipates and erodes leaving the unprotected granules exposed to the hot water. In between pulses, the grounds are exposed to gradual draining of the water and semi-drying as the water pulses flow through the brewing chamber. Each successive pulse aids in achieving a more complete wetting of the grounds as the grounds are agitated by the flowing water, resulting in a much more consistent brewing operation.
U.S. Pat. No. 6,148,717 to Lassota describes a beverage maker with intermittent beverage liquid dispenser and apparatus and method for uniform contact of brew ingredient with brew. Lassota discloses a beverage brewer where a programmable dispenser controller intermittently passes liquid to a dispenser head during pre-selected duty portions of a plurality of control periods in order to control the quantity of liquid dispensed and the duration of the dispense period. The controller includes a microprocessor for controlling the dispensing valve pursuant to a computer program to automatically adjust the duty portions to maintain a pre-selected dispense period during different total dispense quantities and to maintain a pre-selected total dispense quantity for different selected dispense time periods. The control periods are generated by a dividing means that divides the total dispensing period into a plurality of uniform control periods. The control periods are then divided into duty portions and non-duty portions that create the pulse brewing feature. The creation of uniform control periods by dividing the overall brewing period limits the period of the cycles to integer multiples of the overall brewing period.
U.S. Pat. No. 5,375,508 to Knepler includes a control module that allowed the entry of control limits that regulated flow from a heated water source to an infusion assembly, establishing a dispensing cycle that periodically dispensed water from the heated source to the infusion assembly. The pulses of water provided to the infusion assembly are entered by the user and stored in the controller's memory. For example, the user can cause the valve to open at T0 and close at T0 plus sixty seconds, and then open again at T0 plus seventy seconds and close at T0 plus one hundred thirty seconds. The references of Knepler and Lassota are incorporated in full herein by reference.
Another method of maximizing the wetting of the coffee grounds is by pre-infusion or pre-wetting of the coffee prior to brewing. By introducing an initial spray of heated water on the grounds and allowing a short soaking period, the grounds are more efficiently wetted during the brewing cycle. It is preferable to perform either pulse-brewing or pre-infusion prior to the brewing cycle, but not both.
The selection of the appropriate periods of pulse brewing or pre-infusion is dependent upon various factors and the typical consumer is not familiar with the conditions that would favor one pulse brewing sequence over another or the choice between pulse brewing and pre-infusion. The prior art lacks a brewing apparatus that incorporates several predetermined brewing profiles for various conditions that allow the user to simply select a profile and the brewing apparatus will apply the pulse brew profile or pre-infusion sequence based on information stored in its memory. Alternatively, the brewing apparatus can store global instructions that include pulse brew or pre-infusion options, and further include other brewing options and parameters that works best for the present conditions.